In order to explore the effect of boundary layer thickness and pressure gradient on the performance of the flow field in the inlet, we design a high offset rate S-shaped inlet based on a certain unmanned aerial vehicle (UAV), and its author has analyzed the effect of boundary layer characteristics on the inlet with numerical simulation method. The suction of boundary layer which leads to separation zone not only becomes longer in the inlet, but also moves to the center plane of symmetry, the separation point of boundary layer appears in advance as pressure gradient increases. Considering the influence of the boundary layer, various performance parameters all exceeds that of the uniform entrance inlet conditions, especially the circumferential total pressure distortion of outlet increased by 58.2% at most, obviously can't meet the engine to work properly, so we must consider and pay attention to the effect of the boundary layer characteristics on the flow field in the S-shaped inlet.
